In general, a mobile communication system has been developed with the purpose of providing communication while securing the mobility of a user. Such a mobile communication system has come to a stage capable of providing high-speed data communication service in addition to voice communication with the help of the rapid progress of the technology.
Recently, as one of next-generation mobile communication systems, a standardization task for a long term evolution (LTE) system is in progress in the 3rd generation partnership project (3GPP). The LTE system is a technology for implementing high-speed packet-based communication having a transfer rate of a maximum of about 100 Mbps higher than a current data transfer rate, and the standardization of the LTE system has almost been completed.
Recently, a discussion about an advanced LTE communication system (LTE-advanced, LTE-A) which enhances the transfer rate by grafting several new technologies into the LTE communication system is being regularized. A representative one of the technologies to be newly introduced may be a carrier aggregation. Unlike in a conventional technology in which a terminal sends and receives data using only one forward carrier and one backward carrier, in the carrier aggregation, one terminal uses a plurality of forward carriers and a plurality of backward carriers.
Today, in LTE-A, only an intra-eNB carrier aggregation has been defined. In the case of the intra-eNB carrier aggregation, it is apprehended that if one eNB is incapable of service due to an obstacle or load, a terminal in a corresponding area may not be provided with a communication service. Accordingly, there is a need for the definition of the inter-eNB carrier aggregation.